Method and process of contact to a heat softened solder ball array

ABSTRACT

A method for enhancing temporary solder ball connection comprises the application of thermal energy to the solder balls, heating them to a submelting “softening” temperature, whereby the compression force required to connect all balls in a BGA is achieved at much reduced force, avoiding damage to the package, insert, substrate and support apparatus. Several forms of heating apparatus, and temperature measuring apparatus are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of application Ser. No.09/892,156, filed Jun. 26, 2001, pending, which is a continuation ofapplication Ser. No. 09/618,885, filed Jul. 18, 2000, now U.S. Pat. No.6,329,637 B1, issued Dec. 11, 2001, which is a continuation ofapplication Ser. No. 09/145,832, filed Sep. 2, 1998, now U.S. Pat. No.6,121,576, issued Sep. 19, 2000.

BACKGROUND OF THE INVENTION

[0002] Field of the Invention

[0003] This invention relates generally to semiconductor chip packages.More particularly, the present invention pertains to methods forelectrical contact of an array of solder balls with a noncompliantsurface.

[0004] State of the Art

[0005] The testing of packaged semiconductor devices has alwayspresented problems to device manufacturers. Various types of tests maybe conducted at different stages of manufacture. In the current state ofthe art, “wafer sort” electrical tests may be conducted prior topackaging to determine nonworking dies. Following packaging, varioustests including environmental tests as well as parametric and functionalelectrical tests may be performed. A final test which is known as“bum-in” may optionally be conducted. The test includes temperaturecycling over an extended period of time. Essential to the testing ofindividual dies is reliable electrical connection of all die leads tothe test board, without incurring damage to the die or testingapparatus, and easy disassembly from the testing apparatus. While“permanent” wire connections are widely used, wirebonding is timeconsuming and expensive, and also makes the matching of device impedanceto the substrate impedance very difficult to achieve. Much effort isbeing spent on developing alternative methods to reduce the time andexpense of using wire bonds. The replacement of wire bonds with ballgrid array (BGA) connections is becoming more common. Temporaryconductive attachment of solder balls to e.g. a test board is less thansatisfactory.

[0006] Temporary connection of device circuits to a test apparatus isknown to present a variety of problems. The insert member into which asemiconductor die is placed for testing is typically noncompliant, i.e.ceramic or silicon, for example.

[0007] The current method for joining a ball grid array (BGA) to anoncompliant, i.e. rigid surface such as a silicon micromachined pocketinterconnect or insert, is to apply, at ambient temperature, arelatively high compression force of about 22-30 grams-force per solderball. Theoretically, all balls of the array should be pressed intomechanical and electrical contact with the insert pocket. The use ofcompressive forces lower than the above results in a further increasedfrequency of unsatisfactory electrical connections.

[0008] The presence of such unconnected solder balls in a BGA attachmentformed under ambient conditions is believed to be due to a significantvariability in ball diameter and “height” which the industry has beenunable to eliminate. As a result, the applied force of about 22-30grams-force or even more per ball is, in practice, insufficient toensure the required contact of all balls of the array. Furthermore, theuse of compression forces in excess of about 30 grams-force tends todamage the underlying material of the die, insert, and/or substrate. Forexample, effective connection of a 48 ball BGA array using solder ballsof a nominal diameter may require in excess of about 1.5 kg-force. Suchpressures exerted on a die for connection to a ceramic insert may damagethe die and/or insert and/or substrate below the insert. The total forcerequired for connection of larger arrays will be even more. In addition,the use of larger balls not only increases the absolute variation inball diameter but the force required to sufficiently deform each ballfor establishing the required temporary electrical connection. Theproblem also exists with smaller solder balls such as comprise a fineball-grid-array (FBGA) of 0.0125 inches (0.325 mm) diameter balls, forexample. With the smaller diameter solder balls, variation in ballplacement location may have a greater effect than nonuniform balldiameters.

[0009] To date, the industry has continued to use relatively highcompressive forces and necessarily accepted the increased occurrence ofelectrical connection failures of a BGA and/or damage to the die, insertor substrate.

[0010] Ball grid arrays are used in a variety of semiconductor devices.Illustrative of such prior art are U.S. Pat. No. 5,642,261 of Bond etal., U.S. Pat. No. 5,639,695 of Jones et al., U.S. Pat. No. 5,616,958 ofLaine et al., U.S. Pat. No. 5,239,447 of Cotues et al., U.S. Pat. No.5,373,189 of Massit et al., and U.S. Pat. No. 5,639,696 of Liang et al.

[0011] Semiconductor devices having dual sets of outer “leads”, e.g.twin BGA surfaces or a combination of e.g. J-leads and solder bumps, areshown in U.S. Pat. No. 5,648,679 of Chillara et al., U.S. Pat. No.5,677,566 of King et al., and U.S. Pat. No. 5,668,405 of Yamashita.

[0012] Chip carriers of several configurations are described in U.S.Pat. No. 4,371,912 of Guzik, U.S. Pat. No. 4,638,348 of Brown et al.,and Japanese publication 60-194548 (1985).

[0013] Semiconductor devices joined in stacks are disclosed in U.S. Pat.No. 4,868,712 of Woodman, U.S. Pat. No. 4,841,355 of Parks, U.S. Pat.No. 5,313,096 of Eide, U.S. Pat. No. 5,311,401 of Gates, Jr. et al.,U.S. Pat. No. 5,128,831 of Fox, III et al., U.S. Pat. No. 5,231,304 ofSolomon, and U.S. Pat. No. 4,956,694 of Eide.

[0014] U.S. Pat. No. 5,637,536 of Val discloses a chip stackingconfiguration with solder ball connections.

[0015] U.S. Pat. No. 5,012,323 of Famworth discloses a dual-die packagehaving wire interconnections.

[0016] U.S. Pat. No. 4,761,681 of Reid discloses a multi-chip devicehaving elevated (conductor covered mesa) interconnections.

[0017] Despite the advanced state of the art in lead interconnection,device packaging and testing, the temporary connection of semiconductordevices to testing apparatus and burn-in boards remain area which needsimprovement.

BRIEF SUMMARY OF THE INVENTION

[0018] The present invention pertains to methods for electrical contactof an array of solder balls with a noncompliant surface, that is, themechanical and electrical contact of a ball grid array (BGA) to arelatively noncompliant contact set such as a silicon micromachinedpocket interconnect (i.e. “insert”) for a test pad or bum-in board(BIB).

[0019] The present invention further provides a reliable BGA connectionmethod and apparatus whereby the required pressure is much reduced toeliminate or significantly reduce compression-caused damage to the die,insert and/or substrate.

[0020] The present invention comprises methods and apparatus forsoftening solder bumps or balls so that all of the bumps/balls in anarray readily conform to a matching array of conductive contact pocketsor pads in another body. The array of solder bumps/balls is heated to asoftening temperature lower than the melting point of the solder andquickly placed in slightly compressed engagement with the contactpockets or pads of a substrate. As compared to joining the arrays atambient temperature, all bumps/balls of the BGA are reliably connected,and the connection is achieved at a much reduced pressure, avoidingdamage to the die and/or substrate. In addition, much less stress isplaced on the apparatus holding the packaged die, the insert and testboard.

[0021] The softening temperature to which the solder is heated is belowthe melting temperature of the solder alloy.

[0022] A variety of heating apparatus and methods is disclosed,including direct heating of the bumps/balls, heating of the entireassembly, heating of a chuck holding the IC, heating of a chuck holdingthe insert, direct heating of the insert or substrate, etc. Atemperature sensing circuit may also be incorporated into the insert,substrate, or substrate retaining socket for the purpose of measuringand controlling the temperature to which the bumps/balls are heated.

[0023] While electrical contact is readily maintained during electricaltests or bum-in by maintaining a small compressive force, ball contactis easily removed by discontinuing the compressive force and lifting theBGA from the insert or substrate to which it was electrically connected.

[0024] The invention is applicable to a wide variety of soldercompositions, solder bump designs and ball diameters.

[0025] Other features of the invention will become clear from study ofthe following description and related figures.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0026] The invention is illustrated in the following figures, whereinthe elements are not necessarily shown to scale:

[0027]FIG. 1 is a perspective view of an insert assembly for theelectrical testing of a typical flip-chip semiconductor package withBGA, wherein heat enhancement of the BGA connection in accordance withthe invention is shown;

[0028]FIG. 1A is an edge view of a ball grid array on a semiconductorchip;

[0029]FIG. 2 is a perspective view of an insert assembly for theelectrical testing of a typical flip-chip semiconductor package withBGA, showing the package in compressive engagement with the insertassembly for heating enhancement of the BGA connection in accordancewith the invention;

[0030]FIG. 3 is a plan view of a substrate member of the invention;

[0031]FIG. 4 is a bottom view of a substrate member of the invention;

[0032]FIG. 5 is a cross-sectional view of a portion of a heatingassembly of the invention; and

[0033]FIG. 6 is a cross-sectional view of various solder ball contactsites to which the invention may be applied.

DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention relates to method and apparatus embodimentsfor the uniform temporary electrical connection of solder bumps, e.g.solder balls, of a semiconductor device to another body. Rapid thermalsoftening of the solder bumps may be achieved by a variety of specificmethods and apparatus, as described herein. The methods are particularlyuseful for attachment of solder bumps to the surface of a noncompliantbody such as formed of silicon, ceramic, etc.

[0035] As shown in drawing FIG. 1, a semiconductor package 10 isexemplified by a flip-chip package (FCP) with a ball grid array (BGA) 30of a plurality of solder bumps or balls 12 on one surface 14 of thesemiconductor package 10.

[0036] A test apparatus for evaluating circuit performance of thesemiconductor package 10 is shown as including an insert 16 and asubstrate member 18. The insert 16 is noncompliant and is typicallyformed of ceramic or silicon with a pattern of electrical contact sites20 micromachined on its upper surface 22. The contact sites 20 maycomprise simple planar pads, or contact pockets of any configuration, asexplained infra. The contact sites 20 are connected by conductivetraces, not visible, to bond pads 24, the latter being connected by wirebonds 26 to conductive traces 28 on the substrate member 18. The wirebonds 26 and traces 28 on the insert 16 and substrate member 18 may beencapsulated in resin for protection. Other means for connecting thecontact sites 20 to a controller conducting a test, bum-in, etc. may beused, as known in the art.

[0037] The substrate member 18 and attached insert 16 are typicallyinserted into a socket on a test fixture or a bum-in-board (BIB),neither shown in drawing FIG. 1.

[0038] In accordance with the invention, the ball grid array 30 ofsolder bumps/balls 12 is heated and compressed under a slight pressureinto the contact sites 20, shown here as indentations or pockets. Thesolder bumps/balls 12 are heated to a submelting softening temperatureT_(s) and are uniformly contactable to the contact sites 20 by anincreased deformation under the slight compression force.

[0039] In one simple embodiment, an external heater 40 emitting infraredradiation or heated air 42 is positioned to heat the semiconductorpackage 10 including the solder bumps/balls 12 to the desired softeningtemperature, and the BGA 30 is quickly inserted and compressed by force38 into engagement with the contact sites 20 at a relatively lowpressure such as about 2-10 g-force per solder bump/ball 12. Referringto drawing FIG. 1A, of course, the required force per solder bump/ball12 will vary, depending upon the softening characteristics of theparticular solder composition used, the temperature to which the solderbumps/balls 12 are heated, the nominal ball diameter 32, the maximumvariation in ball diameter 32 and the variation in drop distance 34between ball centers 34A and the surface 14 of semiconductor package 10.Typically, the required force 38 at the softening temperature T_(s) toachieve complete ball connection is about 8-25 percent of the force atambient temperature.

[0040] Instead of directly heating the semiconductor package 10 tosoften the solder bumps/balls 12, heat may be applied to the insert 16or substrate member 18 before connecting the BGA 30 to the contact sites20. Also, the semiconductor package 10 may be indirectly heated byapplying thermal energy to a chuck, not shown, which holds the package.

[0041] As shown in drawing FIG. 2, a semiconductor package 10 with anarray of solder bumps/balls 12 is placed on an insert 16, and placedunder a compression force 38. Thermal energy is applied either to theback side 36 of the semiconductor package 10, to the insert 16, to thesubstrate member 18 (as shown in FIGS. 4 and 5), to a compressionmember, not shown, compressing the back side of the semiconductorpackage 10 with force 38, or to a socket, not shown, which surrounds thesubstrate.

[0042] Alternatively, the assembly of semiconductor package 10, insert16 and substrate member 18, together with compression and supportapparatus, may be placed in a temperature controlled oven and rapidlyheated to the desired softening temperature T_(s).

[0043] Thus, the solder bumps/balls 12 may be heated by conduction,convection or radiation, or any combination thereof. For example, anexternal heater 40 (FIG. 1) may heat the semiconductor package 10,insert 16, substrate member 18, or a socket into which the substratemember fits by radiation or heated air 42.

[0044] The solder bumps/balls 12 may be of any diameter 32, includingthose of a fine ball grid array (FBGA), where the balls have a pitch ofless than one (1) mm.

[0045] The solder bumps/balls 12 may be formed of various soldercompositions, including tin-lead solders having a lead content of about30 to 98 percent. Solder compositions having the higher leadconcentrations often have a higher melting point.

[0046] A softening temperature T_(s) of about 130 to about 180 degreesC. has been found useful for reducing the compression force 38 to arelatively low value and simultaneously ensuring electrical contact ofall solder bumps/balls 12.

[0047] As shown in drawing FIG. 3, resistive heating elements 44 may beapplied to the top surface 48 of the substrate member 18, preferablyunder the insert 16 and substantially beneath the semiconductor package10. The heating elements 44 are shown as having power leads 54, 56 forproviding sufficient power to quickly heat the insert 16 including theelectrical contact sites 20, not shown, and the solder bumps/balls 12,not shown, which are in engagement with the contact sites 20.

[0048] All of the conductive traces on substrate member 18, includingconductive traces 28, heater power leads 54, 56, and heating elements 44may be formed simultaneously by screening a thick film of conductivematerial onto the substrate member. This method of forming conductivetraces on a surface is well known in the art.

[0049] A thermocouple junction 50 or other temperature detecting devicemay be installed in or on the insert 16 or substrate member 18 forobtaining temperature feedback and controlling the bump/ball temperatureto attain a maximum desired softening temperature T_(s). Thus, forexample, as shown in drawing FIG. 3, a temperature sensor 50 (such as athermocouple junction) may be fixed on the top surface 48 of thesubstrate member 18 or back side 52 (FIGS. 1 and 2) of the insert 16,and have thermocouple leads 58 connected through otherwise unusedconductive traces 28A, 28B to measurement/control instrumentation, notshown. In use, a heater controller, not shown, determines the measuredtemperature and shuts off (or reduces) power to the heating elements 44upon sensing a predetermined temperature. A recorder, not shown, may beused to calibrate the measurements such that a desired softeningtemperature may be precisely attained.

[0050] A short heating time is preferred, extending only several secondsor less. Most preferably, the heating time is less than one second.Thus, the power leads 54, 56 to the heating elements 44 must besufficiently large to carry the necessary electrical load. In general,installation of the heating elements 44 on the insert 16 will requireseparate power leads 54, 56. Normally, wire bonds 26 (FIG. 1) areincapable of carrying the necessary load.

[0051] Another form of heating apparatus which may be used in theinvention is illustrated in drawing FIGS. 4 and 5. The substrate member18 has on its back side (underside) 46 a pattern of heating elements 44with junctions 62, 64. The junctions 62, 64 may be planar pads orconductively surfaced indentations in the back side 46.

[0052] As shown in drawing FIG. 5, a semiconductor package 10, insert16, and substrate member 18 are positioned in a socket 66 on a testboard 70. Test board 70 may be a board for an electrical test, forburn-in, or other purpose. The socket 66 is typically formed with walls68 and base 72, and many sockets 66 may be mounted on a single testboard 70 to enable simultaneous testing or burn-in of many semiconductorpackages 10.

[0053] A pair of through-holes 74, 76 is formed in the test board 70along axes 84, 86, the axes which pass through junctions 62, 64,respectively. Two metal spring-loaded compression pins 80, also known as“pogo pins”, are mounted in the test board 70 or in another substrate 90underlying the test board. Substrate 90, having a plurality of pogo pins80 projecting therefrom, is known as a bed-of-nails (BON). The pogo pins80 have a base 78 and a spring loaded pin 82 which is axially movablerelative to the base 78. The pins 82 are shown passing through-holes 74,76 to electrically contact the junctions 62, 64 when in compression,power leads 92, 94 from the two pogo pins 80 providing sufficientelectric power to the heating elements 44 for rapidly heating the solderbumps/balls 12. Following testing, the spring-loaded pogo pins 80 willpush the substrate member 18 from the socket 66 with a short stroke.

[0054] In drawing FIG. 6, several types of BGA contact sites 20 areshown as examples illustrating the wide variety of solder bumps/balls 12and contact sites 20 combinations whose temporary connection is enhancedby use of an elevated submelting softening temperature T_(s). Eachsolder bump/ball 12 attached to semiconductor package 10 is configuredto be in compressive conductive contact with a contact site 20.

[0055] Contact site 20A comprises a flat pad or surface of the insert16.

[0056] Contact site 20B is a spherical indentation in the insert 16.

[0057] Contact site 20C is a shallow spherical indentation.

[0058] Contact site 20D is a spherical indentation having a centralaxially directed projection 96 which punctures and enters the softenedsolder bump/ball 12. Preferably, the projection 96 is pyramidal inshape.

[0059] Contact site 20E is a spherical indentation having several,typically four, peripheral projections 98 which contact and are forcedinto the circumferential surface of the solder bump/ball 12.

[0060] The illustrated contact sites 20 to which the invention may beapplied are exemplary only and not exhaustive.

[0061] It is clear that a wide variety of apparatus may be used forheating ball-grid-array connections, of which those described herein arerepresentative.

[0062] The invention has been illustrated in application to the testingof a flip-chip device. However, the temporary BGA connection of anydevice, including other chip scale packages (CSP), is enhanced by thisprocess and apparatus.

[0063] It is apparent to those skilled in the art that various changesand modifications, including variations in heating procedures andstructures, may be made to the BGA connection method and apparatus ofthe invention as described herein without departing from the spirit andscope of the invention as defined in the following claims.

What is claimed is:
 1. A method for connecting at least one solidconductive solder bump of an array of solid conductive solder bumps on asemiconductor device and at least one conductive contact site of aplurality of conductive contact sites of a first member, comprising:providing a semiconductor device having an array of solid conductivesolder bumps; providing a first member having a plurality of conductivecontact sites heating said at least one solder bump of said array ofsolid conductive solder bumps to a softening temperature T_(s) below amelting temperature of said at least one solder bump of said array ofsolid conductive solder bumps; and contacting at least one conductivecontact site of said plurality of conductive contact sites by at leastone solder bump of said array of solid conductive solder bumps of saidsemiconductor device using a pressure less than substantially 22grams-force for the at least one solid conductive solder bump andanother solid conductive solder bump said array of solid conductivesolder bumps.
 2. The method of claim 1, wherein said melting temperatureof said array of solid conductive solder bumps is T degrees Centigradehigher than an ambient temperature T_(o), and wherein the softeningtemperature T_(s) is in the range of about 0.5T to 0.95T above theambient temperature T_(o).
 3. The method of claim 1, wherein said atleast one solid conductive solder bump of said array of solid conductivesolder bumps contacts said at least one conductive contact site of saidplurality of conductive contact sites at a pressure not substantiallyexceeding about 10 grams-force.
 4. The method of claim 1, wherein saidat least one solid conductive solder bump of said array of solidconductive solder bumps contacts said plurality of conductive contactsites at a pressure of in the range of about 2 to 10 grams-force.
 5. Themethod of claim 1, wherein said semiconductor device having said arrayof solid conductive solder bumps is directly heated by one of hot airconvection and infrared radiation.
 6. The method of claim 1, whereinsaid first member having said plurality of conductive contact sites isdirectly heated by said one of hot air convection, conduction from aheated object, and said infrared radiation.
 7. The method of claim 1,wherein said semiconductor device and said first member are placed in atemperature controlled oven for heating to the softening temperatureT_(s).
 8. The method of claim 1, wherein said semiconductor device isheld in a chuck, said chuck being heated.
 9. The method of claim 1,wherein said first member is held in a chuck, said chuck being heated.10. The method of claim 1, wherein said at least one solid conductivesolder bump of said array of solid conductive solder bumps of saidsemiconductor device contacts said at least one conductive contact siteof said plurality of conductive contact sites of said first member beingheated under compressive force to soften said at least one solidconductive solder bump of said array of solid conductive solder bumpsfor connection to said at least one conductive contact site of saidplurality of conductive contact sites.
 11. The method of claim 1,wherein said first member having said plurality of conductive contactsites is heated by electrical resistance wires.
 12. The method of claim1, wherein said first member and a substrate are mounted on a mountingboard having an integral heater, said integral heater controlled to heatsaid first member to said softening temperature T_(s).
 13. The method ofclaim 1, wherein said array of solid conductive solder bumps compriseSn-Pb solder having a lead content in the range of about 40 to about 98percent, and said softening temperature T_(s) comprises a range of about140 to 180 degrees C.
 14. The method of claim 1, wherein said heatingcomprises predetermining a heating time X to heat said at least onesolid conductive solder bump of said array of solid conductive solderbumps to said softening temperature T_(s), and heating for said time X.15. The method of claim 1, wherein said heating comprises initiatingsaid heating, measuring a temperature of one of an insert, a die, and asubstrate being heated, and stopping said heating to limit thetemperature of said at least one solid conductive solder bump of saidarray of solid conductive solder bumps to no more than said softeningtemperature T_(s).
 16. A temporary method to attach at least oneconductive solder bump of an array of conductive solder bumps on asemiconductor device to at least one conductive contact site of aplurality of conductive contact sites of a first member, comprising:providing a semiconductor device having an array of conductive solderbumps; providing a first member having a plurality of conductive contactsites; heating said at least one conductive solder bump of said array ofconductive solder bumps to a softening temperature T_(s) below a meltingtemperature of said at least one conductive solder bump of said array ofconductive solder bumps; and compressing at least one conductive solderbump of said array of conductive solder bumps on said semiconductordevice to at least one conductive contact site of said plurality ofconductive contact sites at a pressure less than substantially 22grams-force and another conductive solder bump of said array ofconductive solder bumps.
 17. The method of claim 16, wherein saidmelting temperature of said at least one conductive solder bump of saidarray of conductive solder bumps is T degrees Centigrade higher than anambient temperature T_(o), and wherein said at least one conductivesolder bump of said array of conductive solder bumps is heated to saidsoftening temperature T_(s) is in the range of about 0.5T to 0.95T abovethe ambient temperature T_(o).
 18. The method of claim 16, wherein saidat least one conductive solder bump of said array of conductive solderbumps is compressed to said at least one conductive contact site of saidplurality of conductive contact sites at a pressure not exceeding about10 grams-force.
 19. The method of claim 16, wherein said at least oneconductive solder bump of said array of conductive solder bumps iscompressed to said at least one conductive contact site of saidplurality of conductive contact sites at a pressure in the range ofabout 2 to 10 grams-force.
 20. The method of claim 16, wherein saidsemiconductor device having said array of conductive solder bumps isdirectly heated by one of hot air convection and infrared radiation. 21.The method of claim 16, wherein said first member having said pluralityof conductive contact sites is directly heated by one of hot airconvection, conduction from a heated object, and infrared radiation. 22.The method of claim 16, wherein said semiconductor device and said firstmember are placed in a temperature controlled oven for heating to thesoftening temperature T_(s).
 23. The method of claim 16, wherein saidsemiconductor device is held and heated for transfer to saidsemiconductor device.
 24. The method of claim 16, wherein said firstmember is held and heated for heat transfer to said first member to heatsaid at least one conductive contact site of said plurality ofconductive contact sites.
 25. The method of claim 16, wherein said atleast one conductive solder bump of said array of conductive solderbumps of said semiconductor device is compressed to said at least oneconductive contact site of said plurality of conductive contact sites ofsaid first member being heated under compressive force to soften said atleast one conductive solder bump of said array of conductive solderbumps for connection to said at least one conductive contact site ofsaid plurality of conductive contact sites.
 26. The method of claim 16,wherein said first member having said plurality of conductive contactsites is heated by electrical resistance wires.
 27. The method of claim16, wherein said first member and a substrate are mounted on a mountingboard having an integral heater, and said integral heater is controlledto heat said first member to said softening temperature T_(s).
 28. Themethod of claim 16, wherein said array of conductive solder bumpscomprise Sn-Pb solder having a lead content in the range of about 40 toabout 98 percent, and said softening temperature T_(s) comprises a rangeof about 140 to 180 degrees Centigrade.
 29. The method of claim 16,wherein said heating comprises predetermining a heating time X to heatsaid array of conductive solder bumps to said softening temperatureT_(s), and heating for said time X.
 30. The method of claim 16, whereinsaid heating comprises measuring a temperature of one of an insert, adie, and a substrate being heated, and stopping said heating to limit atemperature of said array of conductive solder balls to said softeningtemperature T_(s).
 31. An apparatus for temporarily connecting at leastone solder ball of at least one conductive contact site, said apparatuscomprising: a first member having at least one solder ball thereon; asecond member having at least one conductive contact site; apparatus formoving said first member against said second member for contact of saidat least one solder ball to said at least one conductive contact site,said first member contacting said second member at a pressure less thansubstantially 22 grams-force for said at least one solder ball; andheating apparatus for heating said at least one solder ball and said atleast one conductive contact site to a submelting solder softeningtemperature T_(s).
 32. The apparatus of claim 31, wherein said at leastone conductive contact site comprises a substantially flat surface. 33.The apparatus of claim 31, wherein said at least one conductive contactsite comprises a recess for receiving a portion of a solder ball. 34.The apparatus of claim 31, wherein said at least one conductive contactsite comprises a recess having at least one projection therein fordeforming a solder ball inserted therein.
 35. A testing apparatus for asemiconductor package having a ball grid array of solder balls on asurface thereof, said apparatus comprising: an insert formed ofgenerally noncompliant material, said insert having a first surfaceincluding an array of conductive contact sites for contacting said ballgrid array of solder balls, and having a second surface; a substratehaving a first surface, having a second surface, said second surface ofsaid insert secured to said first surface of said substrate, and havinga pattern of conductive leads on said substrate for connecting tocontact leads in a socket; electrical leads connecting said array ofconductive contact sites of said insert with said pattern of conductiveleads of said substrate; a test board having said socket with saidcontact leads to a testing circuit, said substrate and said insertinsertable into said socket for contact of said pattern of conductiveleads of said substrate with said contact leads of said socket; andheating apparatus associated with at least one of said substrate, saidinsert and said socket.
 36. The apparatus of claim 35, furthercomprising: power supply leads providing electrical power to saidheating apparatus.
 37. The apparatus of claim 35, wherein said heatingapparatus comprises resistance conductors.
 38. The apparatus of claim35, further comprising a switch apparatus for turning said heatingapparatus on and off.
 39. The apparatus of claim 35, further comprisingtemperature sensing apparatus attached to one of said substrate, saidinsert, and said semiconductor package.
 40. The apparatus of claim 39,further comprising a temperature controller for controlling said heatingapparatus.
 41. The apparatus of claim 39, wherein said temperaturesensing apparatus comprises a thermocouple junction.
 42. The apparatusof claim 35, wherein said heating apparatus includes a conductive layerof metal deposited on one of said first and second surfaces of saidsubstrate.
 43. The apparatus of claim 36, wherein said heatingapparatus, said power supply leads and conductive leads are formed onsaid substrate.
 44. An temporary connection apparatus for at least onesolder ball on a first member to a corresponding contact site on asecond member, said second member connected to a third member, saidapparatus comprising: a board having a socket thereon for accepting saidfirst member, said second member, and said third member, said boardhaving at least two through-holes extending therethrough; an heatingconductor mounted on a side of said third member; at least twospring-loaded pogo pins mounted to project a pin portion upwardlythrough each of said at least two through-holes for contacting saidthird member; and power leads connecting each pogo pin of said at leasttwo spring-loaded pogo pins to a power supply for heating at least oneof said first member, said second member, and said third memberincluding said at least one solder ball and said at least one contactsite.
 45. The apparatus of claim 44, further comprising a temperaturesensor mounted within said first member, said second member, and saidthird member connected to a temperature measuring circuit.
 46. A heatingapparatus for at least one solder ball under a compression force at aconductive contact site for an electrical connection, said apparatuscomprising: a first member having a surface having at least one solderball thereon; a second member having a surface having an array ofconductive contact sites; apparatus for compressing said first memberagainst said second member for contacting said at least one solder ballsaid at least one conductive contact site, said first member compressedagainst said second member at a pressure less than substantially 22grams-force per solder ball; and heating apparatus for heating at leastone of said at least one solder ball and said at least one conductivecontact site to a submelting solder softening temperature T_(s).
 47. Theapparatus of claim 46, wherein each of said plurality of conductivecontact sites comprises a substantially flat surface.
 48. The apparatusof claim 46, wherein each of said plurality of conductive contact sitescomprises an indentation for receiving a portion of said at least onesolder ball of said ball grid array of solder balls.
 49. The apparatusof claim 46, wherein each of said plurality of conductive contact sitescomprises an indentation having at least one projection extendingthereinto.
 50. A testing apparatus for a semiconductor assembly having aball grid array of solder balls on a surface thereof, said apparatuscomprising: an insert formed of generally noncompliant material, saidinsert having a first surface including an array of conductive contactsites for contact with at least one solder ball of said ball grid arrayof solder balls and having a second surface; a substrate having a firstsurface and a second surface, said second surface of said insertattached to said first surface of said substrate, a pattern of leads onsaid substrate for connection to contact leads in a socket; electricalleads connecting said array of conductive contact sites of said inserthaving said pattern of leads of said substrate; a test board having saidsocket and having said contact leads to a testing circuit, saidsubstrate and said insert for insertion into said socket for electricalcontact of said pattern of leads of said substrate with said contactleads of said socket; heating apparatus associated with at least one ofsaid substrate, said insert and said socket; and at least one powersupply lead providing electrical power to said heating apparatus. 51.The apparatus of claim 50, wherein said heating apparatus comprises atleast one resistance conductor.
 52. The apparatus of claim 50, furthercomprising a switch apparatus connected to said heating apparatus forturning said heating apparatus on and off.
 53. The apparatus of claim50, further comprising temperature sensing apparatus attached to one ofsaid substrate, said insert, and said semiconductor package.
 54. Theapparatus of claim 53, further comprising a temperature controller forcontrolling said heating apparatus.
 55. The apparatus of claim 53,wherein said temperature sensing apparatus comprises a thermocouplejunction.
 56. The apparatus of claim 50, wherein said heating apparatusincludes a conductive layer of metal deposited on one of said first andsecond surfaces of said substrate.
 57. The apparatus of claim 50,wherein said heating apparatus, said at least one power supply lead andsaid pattern of leads are formed on said substrate.
 58. A temporaryconnection apparatus for at least one solder ball on a first member toat least one corresponding contact site on a second member, said secondmember connected to a third member, said apparatus comprising: a boardhaving a socket for accepting said first member, said second member, andsaid third member, said board having at least two through-holesextending therethrough and having first and second through-hole axesgenerally perpendicular to said board; at least one heating conductormounted on an underside of said third member, said at least one heatingconductor having junctions positioned intercepting said at least twothrough-hole axes of said first through-hole and said secondthrough-hole extending through said board; at least one spring-loadedpogo pin mounted to project a pin portion upwardly through each of saidat least two through-holes of said board to contact said third member;and at least one power lead for connecting said at least onespring-loaded pogo pin to a power supply for heating said first member,said second member, and said third member including at least one of saidat least one solder ball and said at least one corresponding contactsite.
 59. The apparatus of claim 58, further comprising a temperaturesensor mounted within said first, second and third members connected toa temperature measuring circuit.